Based on observations that most foregut derivatives depend upon mesenchymal-epithelial interactions for normal development and upon glucocorticoids for full expression of differentiation, and upon our recent finding that in fetal lung glucocorticoid effects on epithelia are mediated by a soluble peptide factor produced by the mesenchyme, we propose to determine if glucocorticoid regulation of other foregut derivatives (duodenum, jejeunum, pancreas, salivary glands, and liver) is also dependent upon mesenchymal-epithelial interactions. We shall develop in vitro techniques to culture, separately and together, epithelia and mesenchyme from these organs and determine the effect of glucocorticoids on them. If mesenchymal-epithelial interactions are observed, we shall use coculture and medium transfer approaches to determine if direct cell contact is necessary.